[BUG] gitk error - can't read "arcnos()": no such element in array

[Chris Packham <judge.packham@xxxxxxxxx>]

Hi,

I'm hitting an error with gitk (gitk 1:2.31.1-0ppa1~ubuntu18.04.1) on
a specific git repository.

The repository is slightly odd in that it has some replace refs
configured and multiple root commits. Although another similarly
configured repo doesn't hit the error.

The text from the application error pop-up is:

can't read "arcnos()": no such element in array
can't read "arcnos()": no such element in array
    while executing
"lsearch -exact $arcnos($l) $a"
    (procedure "splitarc" line 21)
    invoked from within
"splitarc $olds"
    (procedure "getallclines" line 33)
     invoked from within
"getallclines file11"
     ("eval" body line 1)
     invoked from within
"eval $script"
    (procedure "dorunq" line 11)
    invoked from within
"dorunq"
    ("after" script)

I've not been able to narrow down a specific reproduction method yet.

Thanks,
Chris